Many work sites, such as engineering work sites and materials handling sites that involve the operation and movement of vehicles, equipment and machinery (for example, trucks, cranes, tractors, forklifts, conveyors, dump vehicles, diggers, crushers, underground mining equipment and the like) often require special measures to minimise risk of injury and other damage, and to meet particular safety requirements.
The prior art includes warning systems such as proximity detection and collision avoidance systems that have been developed to assist workers or equipment operators to detect the proximity of another worker or machinery so as to avoid collision. However, many work sites are located in harsh environments which may afford poor visibility, noisy or poor sound transmission, and/or be prone to radio signal interference. For these and various other reasons, many existing proximity detection systems have been of limited effectiveness in some work places. In some cases, the signals generated by these proximity detection systems can be weak or otherwise difficult to detect, prone to interruption, and/or prone to interference.
The present invention aims to address at least in part one or more of the disadvantages or problems described above, or at least to provide the relevant industries with a useful choice.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date:                1. part of common general knowledge; or        2. known to be relevant to an attempt to solve any problem with which this specification is concerned.        